dm: remove duplicate dm_get_live_table() in __dm_destroy()

[3.18.y only, to fix a previous patch]

__dm_destroy() takes io_barrier SRCU lock (dm_get_live_table) twice
which leads to a deadlock.  Remove taking lock before holding
suspend_lock to prevent a different potential deadlock.

Signed-off-by: Corey Wright <undefined@pobox.com>
Fixes: e1db66a5fdcc ("dm: fix AB-BA deadlock in __dm_destroy()")
Cc: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 00c86ff..3955df0 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2589,7 +2589,6 @@ static void __dm_destroy(struct mapped_device *md, bool wait)
        might_sleep();
 
        spin_lock(&_minor_lock);
-       map = dm_get_live_table(md, &srcu_idx);
        idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
        set_bit(DMF_FREEING, &md->flags);
        spin_unlock(&_minor_lock);